Fading signals add urgency to search for missing Malaysian jet

The search for a missing Malaysia Airlines jetliner resumed on Saturday, five weeks after the plane disappeared from radar screens, amid fears that batteries powering signals from the black box recorder on board may have died.

Australian Prime Minister Tony Abbott warned on Friday that signals picked up during the search in the remote southern Indian Ocean, believed to be "pings" from the black box recorders, were fading.

Search officials say they are confident they know the approximate position of the black box recorder, although they have determined that the latest "ping', picked up by searchers on Thursday, was not from the missing aircraft.

Batteries in the black box recorder are already past their normal 30-day life, making the search to find it on the murky sea bed all the more urgent. Once they are confident they have located it, searchers then plan to deploy a small unmanned "robot" known as an Autonomous Underwater Vehicle.

"Work continues in an effort to narrow the underwater search area for when the Autonomous Underwater Vehicle is deployed," the Australian agency coordinating the search said on Saturday.